Manually and electrically operated potentiometer



D. A. OLSON Dec. 26, 1967 MANUALLY AND ELECTRICALLY OPERATED POTENTIOMETER 2 Sheets-Sheet 1 Filed Feb. 23, 1967 INVENTOR. 04 v10 4. 04 $0M Dec. 26, 1967 D. A. OLSON 3,360,755

MANUALLY AND ELEGTRICALLY OPERATED POTENTIOMETER Filed Feb. 23, 1967 2 Sheets-Sheet 2 United States Patent ABSTRACT OF THE DISCLOSURE A potentiometer has a straight line resistance element,

along which an electric contact can be moved by a man ually operable slide. The slide also can be moved by a rotatable screw extending lengthwise of the resistance element and operatively connected with the slide.

It is among the objects of this invention to provide a potentiometer that can be operated either manually or electrically, and which is simple and inexpensive in construction.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is a side view, partly broken away;

FIG. 2 is a combined plan view and horizontal section taken on the line 11-11 of FIG. 1;

FIG. 3 is an end view;

FIG. 4 is a vertical section taken on the line IV-IV of FIG. 1; and

FIG. 5 is a side view of a modification.

Referring to FIGS. 1 to 4 of the drawings, an elongated housing 1, rectangular in cross section, is provided in its top with a longitudinal slot 2 and in its bottom with a similar slot 3. Inside the housing an electrical resistance element 4 is attached to the base at one side of slot 3, while a parallel metal current collecting wire or strip 5 is mounted on the base at the opposite side of the same slot. The ends of the resistance element are connected to electric terminals 6 extending out of the housing, and one end of the collector strip likewise is connected to a similar electric terminal 7. The other end of the strip can be connected to a similar terminal if desired.

The block-like body 9 of a slide of insulating material inside the housing has an actuating button 10 extending up through slot 2 so that the slide can be moved lengthwise of the housing by hand. The slide body is recessed to hold a metal contact provided with spring fingers 11 and 12 pressing, respectively, against the collector strip and resistance element. The slide also is provided with an extension 13 that projects down through slot 3. The lower end of the extension has an upwardly extending slot 14 in it forming a fork that receives a tiny worm gear 15 rotatably mounted in the opposite sides of the fork on an axis extending transversely of the housing. The gear meshes with the thread of a lead screw 16 that extends lengthwise of the housing. The ends of the screw are rotatably mounted in parallel brackets 17 and 18 integral with or secured to the ends of housing 1. The screw can be turned from one end by a knob if desired, but preferably by an electric motor 19 mounted on bracket 17. This motor can be controlled by a nearby switch or by a conventional remote control system. The construction of the motor and the way in which it is controlled form no part of this invention.

When screw 16 is stationary, the slide can he slid back and forth in housing 1 by simply moving button 10 with the fingers of the hand. The engagement of the gear and screw will not prevent this, because the gear can turn in the slide fork and thus roll along the screw. It is a feature of this invention, however, that if the screw is rotated 3,360,755 Patented Dec. 26, 1967 it will move the slide in the housing. To accomplish this, the gear must be prevented from rotating so that the screw can cause the gear to move lengthwise of the screw. Rotation of the gear is stopped by a friction brake in the form of a friction member carried by the slide and pressing against the gear. Preferably, the friction member is a slightly bowed leaf spring 21 compressed between one side of the gear and the adjoining side of slot 14-. The ends of the spring project from the sides of the slot and are bent outwardly against the fork to prevent endwise movement and tilting of the spring. The spring rests on the underlying hub of the gear.

Although the pressure of the spring against the gear is sufiicient to prevent the gear from turning when the screw is rotated, when the slide is moved by its button the gear will rotate in sliding engagement with the spring. Consequently, the slide can be adjusted along the housing either by hand through button '10, or mechanically through the lead screw.

This potentiometer has a minimum of parts, considering its dual system of operation, and therefore is relatively inexpensive but reliable and durable.

In the modification shown in FIG. 5, the base of housing 23 supports a resistance element and a collector strip like the ones in FIG. 2. They have terminals 24. The housing has a longitudinal slot in its base, instead of its top, for accommodating the button 25 of a slide (not shown) inside the housing. The slide carries a suitable metal contact for engaging the two strips. Rigidly mounted on the top of the housing is a U-shape bracket 26, in the parallel ends of which a lead screw 27 is journaled. Meshing with this screw is a worm gear 28 rotatably mounted in the slide extension which projects through slots in the top of the housing and the bracket. The screw can be turned by a motor 29 secured to one end of the bracket. This potentiometer can be operated manually or by the motor in the same way as the one first described. The tips of bracket 26 are used for fastening the unit to a mounting panel.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A potentiometer comprising a straight line resistance element, a current collector strip parallel to said element, a slide, an electric contact carried by the slide in engagement with said element and strip, a button projecting from the slide for moving it back and forth along the resistance element and collector strip, a lead screw extending lengthwise of said element, means at opposite ends of the screw pivotally supporting it for rotation on its axis, means for rotating the screw, a gear meshing with the thread of the screw and rotatably connected to the slide on an axis extending transversely of the screw, and a friction member fastened to the slide and pressing against the gear tightly enough to hold it stationary relative to the slide while the screw is being rotated but permitting the gear to rotate and move along the screw when the slide is moved by said button.

2. A potentiometer according to claim 1, in which said screw-rotating means is an electric motor.

3. A potentiometer according to claim 1, in which said friction member is a spring.

4. A potentiometer according to claim 3, in which said spring is compressed between one side of the gear and said slide.

5. A potentiometer according to claim 3, in which said slide is provided with a slot containing said gear, and said spring is a leaf spring inside of the slot and compressed between one side of it and the adjoining side of the gear.

6. A potentiometer according to claim 1, including a housing containing said resistance element and collector strip and provided with a pair of slots parallel thereto, said button extending out through one of the housing slots and said slide being provided with an extension extending out through the other housing slot, said gear being connected to said slide extension outside of the housing.

7. A potentiometer according to claim 6, in which said screw-supporting means are brackets projecting from said housing.

8. A potentiometer according to claim 6, in which said screw-supporting means are brackets projecting from said housing, and said screw-rotating means is an electric motor mounted on one of said brackets and operatively connected to one end of the screw.

9. A potentiometer according to claim 6, in which said screw-supporting means is a bracket secured to the housing and having parallel end portions extending away from the housing, the screw being journaled in said end portions.

10. A potentiometer according to claim 9, in which the ends of said bracket end portions form means for attaching the potentiometer to a support.

References Cited ROBERT K. SCHAEFER, Primary Examiner.

20 H. I. HOHAUSER, Assistant Examiner. 

1. A POTENTIOMETER COMPRISING A STRAIGHT LINE RESISTANCE ELEMENT, A CURRENT COLLECTOR STRIP PARALLEL TO SAID ELEMENT, A SLIDE, AN ELECTRIC CONTACT CARRIED BY THE SLIDE IN ENGAGEMENT WITH SAID ELEMENT AND STRIP, A BUTTON PROJECTING FROM THE SLIDE FOR MOVING IT BACK AND FORTH ALONG THE RESISTANCE ELEMENT AND COLLECTOR STRIP, A LEAD SCREW EXTENDING LENGTHWISE OF SAID ELEMENT, MEANS AT OPPOSITE ENDS OF THE SCREW PIVOTALLY SUPPORTING IT FOR ROTATION ON ITS AXIS, MEANS FOR ROTATING THE SCREW, A GEAR MESHING WITH THE THREAD OF THE SCREW AND ROTATABLY CONNECTED TO THE SLIDE ON AN AXIS EXTENDING TRANSVERSELY OF THE SCREW, AND A FRICTION MEMBER FASTENED TO THE SLIDE AND PRESSING AGAISNT THE GEAR TIGHTLY 